Connectome

The human brain’s wiring diagram – with 100 trillion connections between neurons – is called the “connectome”. The idea has been around since the 1960’s but there is a new explosion in understanding.

The last time there was this much excitement was in 1986 when Sydney Brenner, Nobel Laureate, was given the entirety of The Philosophical Transactions of the Royal Society of London (this was Isaac Newton’s venue). Brenner published “the Book” where he documented the mapping of a transparent worm and its 302 neurons.

Even so, “The race to map the connector has hardly left the starting line”.

“If the cells and fiber in one human brain were all stretched out end to end, they would certainly reach to the moon and back. Yet the fact that they are not arranged end to end enabled man to go there himself. The astonishing tangle within our heads makes us what we are.”
–Colin Blakemore, a physiologist from the UK

Since 2005, Sebastian Seung at MIT has been trying to map this incredible phenomenon, and NYT Magazine wrote about his work this Sunday, January 11, 2015 (“Mind Games” by Garath Cook). He just left MIT in 2013, and now joins his mentor David Tank at the Princeton Bezos Center for Neural Circuit Dynamics.

He started by studying (in Germany, with two graduate students in 2006) the high-resolution brain imaging analysis of Winfried Denk, a scientist who built a device. The device, according to David Tank, imaged brain tissue with enough resolution to make out the connections between individual neurons. The problem was that the images were very blurry and articulating them, mapping each one, etc was a “herculean effort’. So the big problem to solve was – could this task be automated?

Obviously, this relates to the phenomenal leaps ahead in mapping made possible by computer analysis. Another example of this is the Human Genome Project, which mapped the DNA that provides every cell’s genetic instructions. This was obviously breakthrough work, and following after this work was work on Proteome (proteins), Foldome (folding of proteins). Note the U.S. Government has “The Brain Initiative”, which is a 12-year, $4.5 billion brain-mapping project.

So the “connectome” is the brain’s physical structure, which must be mapped. At the same time, a major effort is underway that is separate – namely, to map the areas of the brain that “light up” and therefore are related to certain cognitive functions.

This reference to “physical structure” is meaningful – because people tend to relate to the brain in terms of movement….a dynamic “flow” like a river, and not a physical structure like a river bed.

Haim Sompolinsky studied this structure to understand “aha” moments in learning. This idea relates to an ancient idea- from Plato and Aristotle – that meaning emerges from the ones between things. And in the 21st century, it appears that their is physical terrain that describes this ancient concept: the likes between neurons (note William James described mental processes as associations).

A typical human neuron has thousands of connections. A neuron can be as narrow as one ten-thousandth of a millimeter and yet it can stretch from one side of the head to the other!

References:

Wikipedia on Connectome

NYT Article on Connectome

Santiago Ramon y Cajal – illustrations of neurons and neural networks

Nobel Laureate Sydney Brenner mapped the 302 neurons of a transparent worm in the seventies. He wanted to understand how behaviors emerges from a biological system.

EyeWire – online game that challenges the public to trace neuronal wiring in the retina of a mouse’s eye (has 165,000 players in 164 countries).

connectionism – a cross-disciplinary idea that simple units, connected in the right ways, can lead to surprising abilities (memory, recognition, reasoning).

Harald Hess – a genius in creating scientific tools.”MERLIN” – new brain imaging system. Janella Reseach Campus. They believe they will have mapped a fruit fly’s neural network within two years

Google: announced in September, 2014 at the White House that they had launched their own connector project. Tom Dean is a Google Research Scientist, who also works with the Allen Institute. He wants the “Google Earth of the Brain”!!!!